// Also disallow Host, since the promised URL must be absolute.
		if http2asciiEqualFold(k, "content-length") ||
			http2asciiEqualFold(k, "content-encoding") ||
			http2asciiEqualFold(k, "trailer") ||
			http2asciiEqualFold(k, "te") ||
			http2asciiEqualFold(k, "expect") ||
			http2asciiEqualFold(k, "host") {
			return fmt.Errorf("promised request headers cannot include %q", k)
		}
	}